1. Field of the Invention
The present invention relates to a focus adjustment mechanism and method for a focusing lens of an AF (auto focus) compact camera upon assembly thereof.
2. Description of the Related Art
An AF compact camera has an annular shaped shutter unit. The shutter unit has a female helicoid at the center thereof with which a male helicoid of a lens frame of a focusing lens is engaged. The shutter unit is also provided with an AF driving lever to be rotatively driven along an arc of which its axis is substantially common to that of the female helicoid. The AF driving lever is interlocked with the focusing lens frame via an arm of a ring-shaped connecting member fixed on the lens frame. The AF driving lever is normally maintained at an infinity photographic position, and when the shutter is released, the AF driving lever is driven by an amount corresponding to the object distance information.
Upon assembly of this AF compact camera, the ring-shaped connecting member and the lens frame are allowed to rotate relative to each other, thus the lens frame which is engaged with the shutter unit is moved (rotated) to a predetermined position (for example, an infinity photographic position). Then the AF driving lever as well as the ring-shaped connecting member, which is engaged therewith, are both maintained at the common infinity photographic position. After completion of this adjustment, the lens frame and the ring-shaped connecting member are fixed together (for example, by an adhesive). In the case that the AF compact camera is a zoom lens, a zoom adjustment is further carried out by setting the AF lever at a distance corresponding to an adjusting collimator.
For this focus adjustment upon assembly, in prior arts, a circular groove has usually been formed on the lens frame which only allows rotation of the ring-shaped connecting member by prohibiting movement of the ring-shaped connecting member in an optical axis direction. However, the current AF compact cameras are continuously becoming more and more compact so that there may be a case that it is difficult to form such a circular groove.